refactor(aws-lambda): replace conditional logics with polymorphism (#…

…2521)
honojs · Apr 19, 2024 · c83d80f · c83d80f
1 parent fa9ed80
commit c83d80f
Showing 1 changed file with 135 additions and 75 deletions.
diff --git a/src/adapter/aws-lambda/handler.ts b/src/adapter/aws-lambda/handler.ts
@@ -112,8 +112,9 @@ export const streamHandle = <
 ) => {
   return awslambda.streamifyResponse(
     async (event: LambdaEvent, responseStream: NodeJS.WritableStream, context: LambdaContext) => {
+      const processor = getProcessor(event)
       try {
-        const req = createRequest(event)
+        const req = processor.createRequest(event)
         const requestContext = getRequestContext(event)
 
         const res = await app.fetch(req, {
@@ -156,7 +157,9 @@ export const handle = <E extends Env = Env, S extends Schema = {}, BasePath exte
     event: LambdaEvent,
     lambdaContext?: LambdaContext
   ): Promise<APIGatewayProxyResult> => {
-    const req = createRequest(event)
+    const processor = getProcessor(event)
+
+    const req = processor.createRequest(event)
     const requestContext = getRequestContext(event)
 
     const res = await app.fetch(req, {
@@ -165,105 +168,162 @@ export const handle = <E extends Env = Env, S extends Schema = {}, BasePath exte
       lambdaContext,
     })
 
-    return createResult(event, res)
+    return processor.createResult(event, res)
   }
 }
 
-const createResult = async (event: LambdaEvent, res: Response): Promise<APIGatewayProxyResult> => {
-  const contentType = res.headers.get('content-type')
-  let isBase64Encoded = contentType && isContentTypeBinary(contentType) ? true : false
+abstract class EventProcessor<E extends LambdaEvent> {
+  protected abstract getPath(event: E): string
 
-  if (!isBase64Encoded) {
-    const contentEncoding = res.headers.get('content-encoding')
-    isBase64Encoded = isContentEncodingBinary(contentEncoding)
-  }
+  protected abstract getMethod(event: E): string
 
-  const body = isBase64Encoded ? encodeBase64(await res.arrayBuffer()) : await res.text()
+  protected abstract getQueryString(event: E): string
 
-  const result: APIGatewayProxyResult = {
-    body: body,
-    headers: {},
-    statusCode: res.status,
-    isBase64Encoded,
-  }
+  protected abstract getCookies(event: E, headers: Headers): void
 
-  setCookies(event, res, result)
-  res.headers.forEach((value, key) => {
-    result.headers[key] = value
-  })
+  protected abstract setCookiesToResult(result: APIGatewayProxyResult, cookies: string[]): void
 
-  return result
-}
+  createRequest(event: E): Request {
+    const queryString = this.getQueryString(event)
+    const domainName =
+      event.requestContext && 'domainName' in event.requestContext
+        ? event.requestContext.domainName
+        : event.headers?.['host'] ?? event.multiValueHeaders?.['host']?.[0]
+    const path = this.getPath(event)
+    const urlPath = `https://${domainName}${path}`
+    const url = queryString ? `${urlPath}?${queryString}` : urlPath
 
-const createRequest = (event: LambdaEvent) => {
-  const queryString = extractQueryString(event)
-  const domainName =
-    event.requestContext && 'domainName' in event.requestContext
-      ? event.requestContext.domainName
-      : event.headers?.['host'] ?? event.multiValueHeaders?.['host']?.[0]
-  const path = isProxyEventV2(event) ? event.rawPath : event.path
-  const urlPath = `https://${domainName}${path}`
-  const url = queryString ? `${urlPath}?${queryString}` : urlPath
-
-  const headers = new Headers()
-  getCookies(event, headers)
-  if (event.headers) {
-    for (const [k, v] of Object.entries(event.headers)) {
-      if (v) {
-        headers.set(k, v)
+    const headers = new Headers()
+    this.getCookies(event, headers)
+    if (event.headers) {
+      for (const [k, v] of Object.entries(event.headers)) {
+        if (v) {
+          headers.set(k, v)
+        }
       }
     }
+    if (event.multiValueHeaders) {
+      for (const [k, values] of Object.entries(event.multiValueHeaders)) {
+        if (values) {
+          values.forEach((v) => headers.append(k, v))
+        }
+      }
+    }
+
+    const method = this.getMethod(event)
+    const requestInit: RequestInit = {
+      headers,
+      method,
+    }
+
+    if (event.body) {
+      requestInit.body = event.isBase64Encoded ? Buffer.from(event.body, 'base64') : event.body
+    }
+
+    return new Request(url, requestInit)
   }
-  if (event.multiValueHeaders) {
-    for (const [k, values] of Object.entries(event.multiValueHeaders)) {
-      if (values) {
-        values.forEach((v) => headers.append(k, v))
+
+  async createResult(event: E, res: Response): Promise<APIGatewayProxyResult> {
+    const contentType = res.headers.get('content-type')
+    let isBase64Encoded = contentType && isContentTypeBinary(contentType) ? true : false
+
+    if (!isBase64Encoded) {
+      const contentEncoding = res.headers.get('content-encoding')
+      isBase64Encoded = isContentEncodingBinary(contentEncoding)
+    }
+
+    const body = isBase64Encoded ? encodeBase64(await res.arrayBuffer()) : await res.text()
+
+    const result: APIGatewayProxyResult = {
+      body: body,
+      headers: {},
+      statusCode: res.status,
+      isBase64Encoded,
+    }
+
+    this.setCookies(event, res, result)
+    res.headers.forEach((value, key) => {
+      result.headers[key] = value
+    })
+
+    return result
+  }
+
+  setCookies = (event: LambdaEvent, res: Response, result: APIGatewayProxyResult) => {
+    if (res.headers.has('set-cookie')) {
+      const cookies = res.headers.get('set-cookie')?.split(', ')
+      if (Array.isArray(cookies)) {
+        this.setCookiesToResult(result, cookies)
+        res.headers.delete('set-cookie')
       }
     }
   }
+}
 
-  const method = isProxyEventV2(event) ? event.requestContext.http.method : event.httpMethod
-  const requestInit: RequestInit = {
-    headers,
-    method,
+const v2Processor = new (class EventV2Processor extends EventProcessor<APIGatewayProxyEventV2> {
+  protected getPath(event: APIGatewayProxyEventV2): string {
+    return event.rawPath
   }
 
-  if (event.body) {
-    requestInit.body = event.isBase64Encoded ? Buffer.from(event.body, 'base64') : event.body
+  protected getMethod(event: APIGatewayProxyEventV2): string {
+    return event.requestContext.http.method
   }
 
-  return new Request(url, requestInit)
-}
+  protected getQueryString(event: APIGatewayProxyEventV2): string {
+    return event.rawQueryString
+  }
 
-const extractQueryString = (event: LambdaEvent) => {
-  return isProxyEventV2(event)
-    ? event.rawQueryString
-    : Object.entries(event.queryStringParameters || {})
-        .filter(([, value]) => value)
-        .map(([key, value]) => `${key}=${value}`)
-        .join('&')
-}
+  protected getCookies(event: APIGatewayProxyEventV2, headers: Headers): void {
+    if (Array.isArray(event.cookies)) {
+      headers.set('Cookie', event.cookies.join('; '))
+    }
+  }
 
-const getCookies = (event: LambdaEvent, headers: Headers) => {
-  if (isProxyEventV2(event) && Array.isArray(event.cookies)) {
-    headers.set('Cookie', event.cookies.join('; '))
+  protected setCookiesToResult(result: APIGatewayProxyResult, cookies: string[]): void {
+    result.cookies = cookies
   }
-}
+})()
 
-const setCookies = (event: LambdaEvent, res: Response, result: APIGatewayProxyResult) => {
-  if (res.headers.has('set-cookie')) {
-    const cookies = res.headers.get('set-cookie')?.split(', ')
-    if (Array.isArray(cookies)) {
-      if (isProxyEventV2(event)) {
-        result.cookies = cookies
-      } else {
-        result.multiValueHeaders = {
-          'set-cookie': cookies,
-        }
-      }
-      res.headers.delete('set-cookie')
+const v1Processor = new (class EventV1Processor extends EventProcessor<
+  Exclude<LambdaEvent, APIGatewayProxyEventV2>
+> {
+  protected getPath(event: Exclude<LambdaEvent, APIGatewayProxyEventV2>): string {
+    return event.path
+  }
+
+  protected getMethod(event: Exclude<LambdaEvent, APIGatewayProxyEventV2>): string {
+    return event.httpMethod
+  }
+
+  protected getQueryString(event: Exclude<LambdaEvent, APIGatewayProxyEventV2>): string {
+    return Object.entries(event.queryStringParameters || {})
+      .filter(([, value]) => value)
+      .map(([key, value]) => `${key}=${value}`)
+      .join('&')
+  }
+
+  protected getCookies(
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    event: Exclude<LambdaEvent, APIGatewayProxyEventV2>,
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    headers: Headers
+  ): void {
+    // nop
+  }
+
+  protected setCookiesToResult(result: APIGatewayProxyResult, cookies: string[]): void {
+    result.multiValueHeaders = {
+      'set-cookie': cookies,
     }
   }
+})()
+
+const getProcessor = (event: LambdaEvent): EventProcessor<LambdaEvent> => {
+  if (isProxyEventV2(event)) {
+    return v2Processor
+  } else {
+    return v1Processor
+  }
 }
 
 const isProxyEventV2 = (event: LambdaEvent): event is APIGatewayProxyEventV2 => {